The present invention relates to a radially deployable or expandable flexible preform for forming, after deploying, a tubular structure that is curable by polymerization after positioning in a well or a line, usually hot, such that it moulds to the shape thereof after curing, normally constituting a casing, which is normally substantially cylindrical.
Preforms are already known the walls of which are of flexible materials, that can be folded or compacted on themselves so as to produce a radial dimension that is substantially smaller than the diameter of the well or line to be cased or lined. In the case of a localized repair in a well or pipe, the preform is introduced into the well or line in the folded or compacted state. Once positioned in the desired location, the preform is deployed by outward radial deformation, for example by introducing an inflation fluid such as a gas or a liquid into its interior. The applied pressure causes it to mould to the shape of the well or line. These preforms normally comprise a hot cure resin. In general, the resin forms part of the wall constituting the preform and has usually been introduced by impregnating fibers that contribute to forming that wall. Curing of the resin by hot polymerization can be due to the temperature of the well, but it can also be caused either by introducing a hot fluid into the interior of the preform, or by a Joule effect using suitable electrical resistances disposed in the preform. As an example, electrical resistances forming part of the framework of the wall of the preform impregnated with polymerisable resin can be used. It is also possible to use the heat released by an exothermal reaction that is triggered inside the preform, usually by bringing reactants into contact at the desired moment. It is also possible to introduce a source of electromagnetic radiation, for example microwaves, into the vicinity of the resin.
The preform of the present invention can be positioned and arranged such that cement is not necessary. In the present invention, the term xe2x80x9cflexible preformxe2x80x9d is defined as any assembly preferably with a polymerization initiation system that can maintain a polymerisable resin forming, after polymerization, a constituent element of the future rigid structure of said preform, in a confined medium, preferably between two skins, external and internal, normally of an elastic material. Examples of such preforms have been described in the following patents: French patent applications Nos. 2,753,978 and 2,722,239, and International patent applications Nos. 94/21,887, 91/18,180 and 94/25,655.
The preforms of the invention comprise a polymerisable resin having particular characteristics. Particularly when used in wells and in particular in hot oil wells, the resin must have as high a latent period as possible. Said resin must allow impregnation of the fibers which are a constituent element of said preform using any suitable technique, also storage, transport of said preform, and it must have a positioning period in the well or line (which is usually hot), without the polymerization reaction commencing or advancing too far. It is also vital for the resin used to endow the polymerized preform with good mechanical properties, resistance to hydrothermal ageing (i.e., hydrolysis at the service temperature), a high chemical resistance and as low an absorption as possible in water, petroleum and a variety of effluents present in the service medium.